The project will continue to concentrate on the characterization of selected biochemical constituents that have immunological and physiological importance for the establishment and survival of malaria parasites in their hosts. Two species of malaria, Plasmodium falciparum and P. lophurae, will be used. Our previous studies indicate the presence of immunologically cross-reacting constituents on the surface of erythrocytic and exoerythrocytic merozoites of P. lophurae. We propose to identify unique and shared surface constituents of these two types of merozoites in the hope of getting some insight into stage-specific immunity that has been reported. Our preliminary studies suggest that, unlike erythrocytic merozoites, exerythrocytic merozoites retain their surface coat during entry into host cells. We will attempt to confirm this observation conclusively. In the course of studies on stage-specific proteins of P. falciparum, we identified two constituents that were unique to mature schizonts. We propose to extend these studies in an attempt to identify prospective functional antigens from merozoites of P. falciparum. Utilization of glucose by erythrocytes increases several fold following infection with malaria parasites and this is accompanied by an increase in the permeability of the host cell membrane to glucose. We propose to initiate studies to characterize the molecular basis for permeability changes of host erythrocytes and to answer the fundamental question of how malaria parasites utilize glucose for the synthesis of ATP. If time and means permit, we propose to extend studies on transport properties of the membranes of host cells to examine the relation of altered erythrocyte surface components to the development of chloroquine resistance in P. falciparum.